This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-130927, filed Apr. 28, 2000; and No. 2000-130928, filed Apr. 28, 2000, the entire contents of both of which are incorporated herein by reference.
The present invention relates to an X-ray object detector in which an object to be detected is fed between an X-ray generation part and an X-ray detection part, for receiving X-rays from the X-ray generation part by a conveyer part, and the X-rays which penetrate the object are received by the X-ray detection part, thereby to detect a foreign body or body (contaminant) contained in the object. Particularly, the present invention relates to an X-ray foreign-body detector which uses an X-ray detection unit comprising integrally the X-ray detection part and the conveyor part.
Conventionally, an X-ray foreign-body detector is used to detect foreign bodies (metal, bones, glass, stones, synthetic resin bodies, and the like) which may be erroneously mixed in an object such as fresh meat, processed food, or the like to be subjected to detection.
In this kind of X-ray foreign-body detector, the X-ray generation part is generally installed on the body of the apparatus, and the X-ray generation part is positioned in the lower side of the X-ray generation part in the body of the apparatus.
In this manner, X-rays radiated from the X-ray generation part are received by the X-ray detection part.
Also, the apparatus body is equipped with a conveyor part for feeding an object to be detected under the X-rays radiated as described above.
This conveyor part includes a plurality of rollers provided at front-side and rear-side positions in the conveying direction in the body of the apparatus, and a belt tensioned around the plurality of rollers.
Any of the plurality of rollers serves as a drive roller which is connected with and driven by a drive source such as a motor or the like attached to the apparatus body, and the other rollers serve as slave rollers which are driven by the drive roller.
By driving of the plurality of rollers, the belt tensioned around the plurality of rollers is circularly rotated.
A support plate for supporting the object to be detected is provided in a belt rotated circularly.
Also, the X-ray detection part is provided in the lower side of the belt (e.g., inside the belt rotated circularly).
Further, the upper side of the belt is situated between the x-ray generation part and the X-ray detection part.
In this manner, in the X-ray foreign-body detector, the X-ray generation part radiates X-rays to the object to be detected, which is conveyed on the belt, and the X-ray detection part receives the X-rays, which have penetrated the object to be detected, thereby to detect a foreign body contained in the object to be detected.
However, in the conventional x-ray foreign-body detector described above, the X-ray generation part, x-ray detection part, and conveyor part are attached to the apparatus body.
In particular, the X-ray detection part and the conveyor part are situated to be close to each other, in order to detect a foreign body mixed in the conveyed object subjected to detection.
Therefore, the structure is arranged such that the rollers, belt, support plate, drive source (motor), and the like as components forming the conveyor part are provided and mixed together with the X-ray detection part, at the part of the apparatus body where the X-ray detection part and the conveyor part are installed.
If components having functions different from each other are thus mixed, assembly of the components is complicated and much labor is required for maintenance such as inspecting, repairing, cleaning, and the like, of respective parts.
In particular, with respect to cleaning, food is inspected as an object subjected to detection in some cases. Care is therefore required to maintain hygiene.
However, since the structure is arranged such that components forming the X-ray detection part and the conveyor part are in close proximity as described above, there is a problem in that gaps and seams between component allow for germs to multiply therein.
Although the components need to be disassembled to clean the gaps and seams, the structure is arranged such that the components forming the X-ray detection part and conveyor part combined.
Therefore, in the conventional x-ray foreign-body detector, there is a problem that the respective components cannot be easily disassembled during cleaning.
In addition, in the conventional X-ray foreign-body detector, the X-ray generation part, x-ray detection part, and conveyor part are installed on the apparatus body.
Therefore, the x-ray generation part, X-ray detection part, and conveyor part cannot be assembled without the apparatus body.
That is, in the conventional X-ray foreign-body detector, assembly processes constitute one line which cannot be dispersed into a plurality of lines, resulting in a problem that the manufacturing costs are increased.
FIGS. 16A and 16B are top and side views showing a conventional conveyor.
This conveyor 51 is constructed by a body 52 and an attachable/detachable unit 53 which can be freely attached to and detached from the body 52.
The body 52 is constructed by a pair of side plates 52a and a drive motor 57.
The attachable/detachable unit 53 is constructed by a receive base 54, a drive roller 55a and a slave roller 55b provided in both side parts of the receiver base 54, and a belt 56 tensioned around the rollers 55a and 55b. 
This attachable/detachable unit 53 is kept attached to the body 52, by a fixing tool (for example, a catch clip) 59.
Note that the drive motor 57 is connected with a rotation shaft of the drive roller 55a through a connection belt 58 in order to transmit the rotation of the drive motor 57 to the drive roller 55a. 
With respect to the conveyor 51, maintenance and checks must be carried out. For example, the components of the attachable/detachable unit 53 (e.g., the drive roller 55a and the belt 56) must be periodically cleaned or replaced.
Particularly in the case where the object subjected to inspection is food, parts of the conveyor 51 must be sterilized, disinfected, or the like.
However, in the structure described above, the drive roller 55a or the belt 56 cannot be easily attached or detached, so that disassembly, cleaning, and maintenance cannot be carried out easily.
That is, to detach the belt 56, the connection belt 58 tensioned around the drive roller 55a and the drive motor 57 must be detached.
For example, when screws of the base of the drive motor 57 and the connection belt 58 are detached, a protection cover 58a of the (safety) connection belt 58a must be detached in order to detach the connection belt 58.
At this time, in the state where the protection cover 58a is detached, a risk arises in that the connection belt 58 is openly exposed.
In order to solve this problem, another structure is arranged such that transmission of the drive force between the drive roller 55a and the drive motor 57 of the conveyor 51 is not achieved by the connection belt 58, but is achieved by providing gears respectively for the drive roller 55a and the drive motor 57, to make connection by engagement of the gears.
Thus, also in this structure of using gears, the gears are engaged with each other at a predetermined pitch (precision), and therefore, it is difficult that the conveyor 51 is connected and disconnected by the gear parts.
In this case, if the tooth engagement precision is relaxed by changing the shape of the gears etc., the conveyor 51 can be easily detachable at the gear part. There is however a problem that the transmission characteristics (efficiency and durability) of the drive force are lowered.
The present invention has an object of providing an X-ray foreign-body detector which uses an X-ray detection unit integrally comprising an X-ray detection part and a conveyor part, in order to achieve discreet assembly of each component, and to facilitate maintenance.
Another object of the present invention is to provide an X-ray foreign-body detector which uses an X-ray detection unit integrally comprising an X-ray detection part and a conveyor part in order to achieve discreet assembly of each component and to facilitate maintenance, and which also uses a conveyor which can be disassembled for cleaning or the like through a simple structure.
Further, another object of the present invention is to provide an X-ray foreign-body detector which uses an X-ray detection unit integrally comprising an X-ray detection part and a conveyor part in order to achieve discreet assembly of each component and to facilitate maintenance, and which also uses such a conveyor part in which the conveying distance can be freely changed according to needs.
To achieve the above objects, according to the first aspect of the present invention, there is provided an X-ray foreign-body detector comprising:
a casing (5);
an X-ray generation part (1) provided inside the casing; and
an X-ray detection unit (100) integrally including an X-ray detection part (2), which detects X-rays, and, a conveyor part (3), which conveys an object to be inspected, for detecting a foreign body mixed in the object by receiving the X-rays, which are radiated from the X-ray generation part to the object conveyed by the conveyor part and are transmitted through the object, the X-ray detection part and the conveyor part being integrally attached to a predetermined part of the casing, such that the X-ray detection part and the conveyor part are freely attachable and detachable,
wherein the X-ray detection unit comprises an X-ray detection part container (6) made of metal, which has at least an upper surface (6a), a lower surface (6e) opposed to the upper surface, and front and rear surfaces (6b and 6c) which connect the upper and lower surfaces in both sides in a longitudinal direction, and in which a slit (7) extending in a lateral direction to allow the X-rays to penetrate through the upper surface (6a) is formed in the upper surface, and the X-ray detection part is provided inside,
a front roller support part (11) extending forward in the longitudinal direction of the X-ray detection part container and attached to the X-ray detection part container,
a rear roller support part (12) extending rearward in the longitudinal direction of the X-ray detection part container and attached to the x-ray detection part container,
a front roller (8) detachably and attachably included in the front roller support part,
a rear roller (8) detachably and attachably included in the rear roller support part, and
a conveyor belt (10) tensioned around the front and rear rollers, surrounding the X-ray detection part container, and supported on the upper surface of the X-ray detection part container in a state in which the object is mounted thereon,
one of the front and rear rollers being constructed as a drive roller and the other one being constructed as a slave roller.
To further achieve the above objects, according to the second aspect of the present invention, in the detector according to the first aspect, the X-ray detection unit further comprises a drive roller unit provided in parallel with the drive roller, a drive roller, a pair of bearing parts provided at both ends of the drive roller, and a fixing shaft to which the pair of bearing parts are fixed, the drive roller unit being detachably attached to the X-ray detection part container.
To further achieve the above objects, according to the third aspect of the present invention, in the detector according to the second aspect, the X-ray detection part container is provided with engaging grooves in which with one of the bearing parts and the fixing shafts are engaged and positioned to fix the drive roller unit.
To further achieve the above objects, according to the fourth aspect of the present invention, in the detector according to the second aspect of the present invention, the X-ray detection part container is provided with a fixing mechanism which is engaged with the fixing shaft thereby to fix and hold the drive roller unit in relation to the casing.
To further achieve the above objects, according to the fifth aspect of the present invention, in the detector according to the second aspect, the X-ray detection unit further comprises a connection part provided at an end part of a rotation shaft of the drive roller, to transmit the drive force of the motor and to enable separation, such that the drive roller unit can be freely detached and attached by the separation at the connection part.
To further achieve the above objects, according to the sixth aspect of the present invention, in the detector according to the fifth aspect, the connection part is constructed by a pair of couplings fixed respectively to an output shaft of the motor and the rotation shaft of the drive roller, thus transmitting the drive force.
To further achieve the above objects, according to seventh aspect of the present invention, in the detector according to the sixth aspect of the present invention, the x-ray detection unit further comprises a protection case and a receiving section provided for the drive roller and the motor, such that the protection case and the receiving section are respectively coaxial with the pair of couplings, enable positioning of axles of the pair of couplings, and cover the pair of couplings.
To further achieve the above objects, according to the eighth aspect of the present invention, in the detector according to the second aspect, the X-ray detection part is sealed and contained in the X-ray detection part container.
To further achieve the above objects, according to the ninth aspect of the present invention, in the detector according to the eighth aspect, one slave roller among the one driver roller and three slave rollers is arranged at a side part of the X-ray detection part container, the other two slave rollers of the three slave rollers are arranged at another side part of the X-ray detection part container.
To further achieve the above objects, according to the tenth aspect of the present invention, in the detector according to the ninth aspect, engaging grooves in which the two slave rollers arranged at the another side part are engaged are formed in the X-ray detection part container, and a slide plate which can be freely slid is provided in a side of the one side parts.
In the structure described above, bearing parts at both end parts of the drive roller of the conveyor part are integrated by a fixing shaft, and these parts are detachably attached to the X-ray detection part container.
The engaging grooves provided in the X-ray detection part container position the bearing parts and the fixing shaft, so that they can be easily and freely attached to or detached from the casing by operating a fixing mechanism.
In addition, the motor and the rotation shaft of the drive roller can be connected and disconnected by couplings, so the connection and disconnection of the drive force transmission part can be easily carried out. Accordingly, the drive roller unit can be detached and attached more easily.
To further also achieve the above objects, according to the eleventh aspect of the present invention, in the detector according to the first aspect, the roller support parts corresponding to a conveying distance are respectively installed at positions at the front and rear of the X-ray detection part container, and a conveyor belt having a corresponding conveying distance is installed at the same time, thereby making the conveying distance freely changeable.
To further achieve the above objects, according to the twelfth aspect of the present invention, in the detector according to the tenth aspect, the X-ray detection part container is provided with a cover which has a length corresponding to the conveying distance of the conveyor part and prevents leakage of X-rays.
To further achieve the above objects, according to the thirteenth aspect of the present invention, in the detector according to the tenth aspect, an engaging part for engaging and releasing each of the X-ray detection part container and the front and rear roller support parts is provided on a joint surface between the X-ray detection part container and the front and rear roller support parts.
To further achieve the above objects, according to the fourteenth aspect of the present invention, in the detector according to the tenth aspect, a detachably attached drive roller unit, for conveying and driving the conveyor belt, is provided at the front and rear roller support parts, and the drive roller unit comprises a pair of bearing parts provided at both ends of the drive roller, and a fixing shaft provided in parallel with the drive roller, for making the pair of bearing parts respectively fixed to the fixing shaft.
To further achieve the above objects, according to the fifteenth aspect of the present invention, in the detector according to the thirteenth aspect, a connection part which transmits the drive force of a motor, and can be freely separated, is provided at an end part of a rotation shaft of the drive roller.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.